In internal combustion engines and piston compressors, there are in practice observed leakage losses which may be attributed to an incomplete sealing, for example, of the piston/cylinder path or the valve guides in the cylinder head. The leakage losses are referred to as blowby gas and contain a substantial amount of oil. With respect to internal combustion engines, it is therefore conventional to direct the blowby gas which occurs during operation of the internal combustion engine back into the intake tract of the internal combustion engine. In order, on the one hand, to minimize the oil loss as a result of the blowby gas and, on the other hand, to ensure optimum combustion and minimal environmental damage, it is known to supply the blowby gas to an oil separator and to direct the separated oil back into the oil circuit. In this instance, it is sought to configure corresponding oil separation systems to be as simple as possible but nevertheless to be reliable and efficient. Another aspect for improving oil separators relates to a minimal flow resistance to which the gas flow is subjected when the oil separator is flowed through. However, a high separation capacity is necessary in order to minimize the output of residual oil in the charge air tract, in particular in order to prevent air mass measuring members and turbochargers from becoming fouled by oil.
DE 10 2009 012 400 A1 sets out an oil separator which is suitable for crankcase ventilation of an internal combustion engine. The oil separator has as the housing a hollow member which can be formed, for example, by a portion of a camshaft or the hollow member is constructed to be tubular and is integrated in a cylinder head cover of an internal combustion engine. A torsion generator is arranged in the hollow member and the hollow member has an end-side supply opening for introducing the gas flow and a discharge opening for discharging the gas flow. The gas flow introduced into the hollow member may also carry oil in the form of oil mist or spray droplets which are intended to be removed from the gas flow by the oil separator. To this end, the hollow space further has a discharge opening which is for discharging separated oil and which is constructed separately from the discharge of the gas flow which has been purged of oil.
In principle, oil separators use a torsion effect which can be used in a particularly advantageous manner when the oil separator is formed in a rotating camshaft which forms the hollow member of the oil separator. To this end, in DE 10 2009 012 400 A1 there is formed in the hollow member a torsion generator which has a plurality of helical flow channels and through which a torsion is introduced into the gas flow which is charged with oil. As a result of the associated change in the flow direction of the gas flow, oil droplets which are also carried in the gas flow are separated on the inner wall of the hollow member and, as a result of the throughflow of the hollow member in the longitudinal direction, the oil droplets reach the outer region of the oil separation ring, by which the gas flow is separated in the central region of the hollow member from the oil flow in the wall region of the hollow member. Finally, after the oil separation ring has been arranged, the oil can be separated by the discharge opening for the oil from the discharge opening of the cleaned gas flow which is subsequently supplied to the discharge tract of the internal combustion engine or, for example, a piston compressor. In order to form the oil separation ring, it is set out that it can be constructed from a porous plastics material or a sintered material, wherein plastics or metal braided material can also be advantageously used. Such braided materials form a large number of hollow spaces and labyrinth-like formations, whereby the separation of the oil from the gas flow is further promoted. As a result of the torsion, the oil droplets are conveyed radially outward in relation to the longitudinal axis of the hollow member and the gas flow is guided through the central passage in the oil separation ring.
As a result of the rotational movement which is introduced into the gas flow by the torsion generator, there is produced during flow through the oil separator a substantial flow resistance in the gas flow, by which the separation power is again reduced by lower flow rates through the oil separator.